数据库的安装初始化及管理

官网下载或者 wget
$root@mysql \~$ # ls
anaconda-ks.cfg
initserver.sh
mysql-8.0.33-1.el7.x86_64.rpm-bundle.tar
mysql-community-client-8.0.33-1.el7.x86_64.rpm
mysql-community-client-plugins-8.0.33-1.el7.x86_64.rpm
mysql-community-common-8.0.33-1.el7.x86_64.rpm
mysql-community-debuginfo-8.0.33-1.el7.x86_64.rpm
mysql-community-devel-8.0.33-1.el7.x86_64.rpm
mysql-community-embedded-compat-8.0.33-1.el7.x86_64.rpm
mysql-community-icu-data-files-8.0.33-1.el7.x86_64.rpm
mysql-community-libs-8.0.33-1.el7.x86_64.rpm
mysql-community-libs-compat-8.0.33-1.el7.x86_64.rpm
mysql-community-server-8.0.33-1.el7.x86_64.rpm
mysql-community-server-debug-8.0.33-1.el7.x86_64.rpm
mysql-community-test-8.0.33-1.el7.x86_64.rpm
确定 mysql-community-server 正常安装之后就可以开始配置
初始化 mysqld 服务 mysqld initeialize
启动服务 systemctl start mysqld
添加开机启动列表 systecmctrl enable mysqld
在 /var/log/mysql.log 中找到初始密码，前后复制空格 7. 登录管理 mysql -uroot -p
将复制的密码粘贴到输入密码的区
域，实现登录
设置新的密码
退出登录

1. 数据库的对象
数据库系统 DBMS
数据库
DB
表
table
记录
record
字段
feild
1. 数据库操作
删除库

创建库
mysql > create datababse test charset utf8;
Query OK, 1 row affected, 1 warning ( 0.01 sec )
mysql > show databases ; 查看库
2. 表的操作
1. 选择库
+--------------------+

mysql > create datababse test charset utf8;
Query OK, 1 row affected, 1 warning ( 0.01 sec )
mysql > show databases ; 查看库
2. 表的操作
1. 选择库

2. 查看表

3. 创建表

mysql > CREATE TABLE `test` . `user` (
-> `id` INT NOT NULL AUTO_INCREMENT ,
-> `username` VARCHAR ( 45 ) NOT NULL ,
-> `password` VARCHAR ( 45 ) NOT NULL ,
-> PRIMARY KEY ( `id` ) ,
-> UNIQUE INDEX `username_UNIQUE` ( `username` ASC )
VISIBLE )
-> COMMENT = 'us' ;
mysql > show tables ;
+----------------+
| Tables_in_test |
+----------------+
| user |
| user0 |
4. 删除表
新增列
mysql > show tables ;
+----------------+
| Tables_in_test |
+----------------+
| user |
| user0 |
+----------------+
2 rows in set ( 0.00 sec )
mysql > drop table user0;
Query OK, 0 rows affected ( 0.01 sec )
mysql > show tables ;
+----------------+
| Tables_in_test |
+----------------+
| user |
+----------------+
1 row in set ( 0.01 sec )
ALTER TABLE `test`.`user`
ADD COLUMN `realname` VARCHAR(45) NULL AFTER `password`;
mysql> desc user;
+----------+-------------+------+-----+---------+---------
-------+
| Field | Type | Null | Key | Default | Extra
|
+----------+-------------+------+-----+---------+---------
-------+
| id | int | NO | PRI | NULL |
auto_increment |
| username | varchar(45) | NO | UNI | NULL |
| 修改列名
| password | varchar(45) | NO | | NULL |
|
| realname | varchar(45) | YES | | NULL |
|
+----------+-------------+------+-----+---------+---------
-------+
4 rows in set (0.01 sec)
mysql> ALTER TABLE `test`.`user`
-> CHANGE COLUMN `realname` `zsxm` VARCHAR(45) NULL
DEFAULT NULL ;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc user;
+----------+-------------+------+-----+---------+---------
-------+
| Field | Type | Null | Key | Default | Extra
|
+----------+-------------+------+-----+---------+---------
-------+
| id | int | NO | PRI | NULL |
auto_increment |
| username | varchar(45) | NO | UNI | NULL |
|
| password | varchar(45) | NO | | NULL |
|
| zsxm | varchar(45) | YES | | NULL |
|
+----------+-------------+------+-----+---------+---------
-------+ 删除列
其他
记录的操作
新增
mysql > ALTER TABLE `test` . `user`
-> DROP COLUMN `zsxm` ;
Query OK, 0 rows affected ( 0.01 sec )
Records: 0 Duplicates: 0 Warnings : 0
mysql > desc user ;
+----------+-------------+------+-----+---------+---------
-------+
| Field | Type | Null | Key | Default | Extra
|
+----------+-------------+------+-----+---------+---------
-------+
| id | int | NO | PRI | NULL |
auto_increment |
| username | varchar ( 45 ) | NO | UNI | NULL |
|
| password | varchar ( 45 ) | NO | | NULL |
|
+----------+-------------+------+-----+---------+---------
-------+
3 rows in set ( 0.00 sec )
#insert into 表名 ( 字段名列表 ) values ( 字段值列表 )
mysql > select * from user ;
Empty set ( 0.00 sec )
mysql > insert into user ( id,username, password ) values
( 3 , 'zhangsan' , 'zhangsan' ) ; Query OK, 1 row affected ( 0.01 sec )
mysql > select * from user ;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
| 3 | zhangsan | zhangsan |
+----+----------+----------+
1 row in set ( 0.00 sec )
mysql > select * from user ;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
| 3 | zhangsan | zhangsan |
+----+----------+----------+
1 row in set ( 0.00 sec )
mysql > insert into
user ( username, password ) values ( 'lisi' , 'lisi' ) ;
Query OK, 1 row affected ( 0.00 sec )
mysql > select * from user ;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
| 3 | zhangsan | zhangsan |
| 4 | lisi | lisi |
+----+----------+----------+
2 rows in set ( 0.00 sec )
mysql > desc user ;
+----------+-------------+------+-----+---------+------
----------+
| Field | Type | Null | Key | Default | Extra
| +----------+-------------+------+-----+---------+------
----------+
| id | int | NO | PRI | NULL |
auto_increment |
| username | varchar ( 45 ) | NO | UNI | NULL |
|
| password | varchar ( 45 ) | NO | | NULL |
|
+----------+-------------+------+-----+---------+------
----------+
3 rows in set ( 0.00 sec )
删除
delte from user where 条件 ;
mysql > delete from user where username = 'zhangsan' ;
Query OK, 1 row affected ( 0.00 sec )
mysql > select * from user ;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
| 4 | lisi | lisi |
+----+----------+----------+
1 row in set ( 0.00 sec )
mysql > delete from user ;
Query OK, 1 row affected ( 0.00 sec ) mysql > select * from user ;
Empty set ( 0.00 sec )
修改
mysql >
mysql > insert into user values
( 1 , 'zhangsan' , 'zhangsan' ) ;
Query OK, 1 row affected ( 0.00 sec )
mysql > insert into user values ( 2 , 'lisi' , 'lisi' ) ;
Query OK, 1 row affected ( 0.00 sec )
mysql > insert into user values ( 3 , 'wangwu' , 'wangwu' ) ;
Query OK, 1 row affected ( 0.00 sec )
mysql > select * from user ;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
| 1 | zhangsan | zhangsan |
| 2 | lisi | lisi |
| 3 | wangwu | wangwu |
+----+----------+----------+
3 rows in set ( 0.00 sec )
mysql > update user set password = 123 where
username = 'zhangsan' ;
Query OK, 1 row affected ( 0.01 sec )
Rows matched: 1 Changed : 1 Warnings : 0
mysql > select * from user ;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
| 1 | zhangsan | 123 | | 2 | lisi | lisi |
| 3 | wangwu | wangwu |
+----+----------+----------+
3 rows in set ( 0.00 sec )
查询